MIL harassing me hours after birth

The Nano second that legal law were brought up means all bets are off. When someone threatens legal action for rights to you child, they have said I will sue you for custody/partial custody of your child.

If they can prove any relationship, they may get a toehold. Now whether they win or not, they can still drag you through the legal mud and ruin you financially.

You need a lawyer, experienced and certified in your jurisdiction, on how to proceed. NY treats GPR as a god given right, FL laughs at them.

Whatever you do, do not try and appease the beast, by offering a peace offering meeting. Save every text and email and FB message, print them out, keep digital copies.